Nitroimidazoles

ABSTRACT

Novel substituted nitroimidazoles are provided, for example, 2(4,5-substituted-isoxazol-3-yl)-1-substituted-5-nitroimidazole; 2-(4,5-disubstituted- Delta 2-isoxazolin-3-yl)-1-substituted-5nitroimidazole; or 2-(4,5-disubstituted-2-(loweralkylisoxazolidin-3-yl)-1-substituted-5 -nitroimidazole. These compounds have antibacterial and antiprotozoal activity especially against human and animal trypanosomiasis and trichomoniasis.

United States Patent Kulsa et al.

NITROIMIDAZOLES Inventors: Peter Kulsa, Scotch Plains, N..l.;

Clarence S. Rooney, Beaconsfield,

Canada Assignee: Merck & Co., Inc., Rahway, NJ.

Filed: Oct. 27, 1972 App]. No.: 301,420

Related US. Application Data Division of Ser. No. 1,307, Jan. 7, 1970,Pat. No. 3,711,495.

US. Cl. 260/307 F; 424/272 Int. Cl. C07D 413/04 Field of Search 260/307F References Cited UNITED STATES PATENTS 1/1973 Kulsa et a]. 260/307 D3,769,295 10/1973 Hoyle et al. 260/307 F Primary ExaminerNorma S.Milestone Assistant Examiner-C. M. S. .laisle Attorney, Agent, orFirm-Edmunde D. Riedl; 1. Jerome Behan [57] ABSTRACT 2 Claims, NoDrawings NITROIMIDAZOLES This is a division of application Ser. No.1,307, filed Jan. 7, 1970, now U.S. Pat. No. 3,711,495, patented Jan.16, 1973.

This invention relates to isoxazol-3-yl-, A isoxazolin-3-yl-, orisoxazolidin-3-yl-substituted-5- nitroimidazoles.

These compounds have the following respective structures:

wherein R, is hydrogen, loweralkyl having l6 carbon atoms, or CH CH OH,Y is loweralkyl having l6 carbon atoms, benzyl, or hydrogen, R and R arethe same or different and are each hydrogen, loweralkyl having l6 carbonatoms, carboxyalkyl, carboxamido, carboxamidoalkyl, carboxamidodialkyl,amino, phenyl, aminoalkyl, aminodialkyl, or R and R are a ring structurehaving the following structure:

-+CH n equals an integer 3-10;

m equals an integer from l3; equals an integer from l2; +CH SO2CH2+ -(CH),,,O m equals an integer from 2-3;

Z equals hydrogen or benzoyl;

n equals an integer from L4;

and R and R are the same or different and are each hydrogen, loweralkylhaving 'l-6 carbon atoms, carboxyalkyl, carboxamido, carboxamidoalkyl,carboxamidodialkyl, amino, phenyl, aminoalkyl, or aminodialkyl; or R andR are a ring structure of -(-CH equals an integer from 3-10; except thatwhen only one of R and R or R and R are hydrogen, the substituent otherthan hydrogen is on the 5-position of the ring. Whenever the term alkylis used throughout the specification, a lower alkyl group having 1-6carbon atoms is intended.

The novel compounds disclosed in this invention are prepared followingthree different processes. The isoxazolyl derivatives are prepared byreacting an acetylene derivative with a 1-loweralky1-5-nitroimidazol- 2-hydroxamoyl chloride.

The A -isoxazolinyl derivatives are prepared by reacting an olefin witha 1-loweralkyl-5-nitroimidazol- 2-hydroxamoyl chloride.

The isoxazolidinyl derivatives are prepared by reacting an olefin withan a-(1-methy1-5-nitroimidazol-2- yl) )-N-alkylnitrone. These processesare separately discussed in greater detail hereinaften The reactiveolefin used to prepare both the A isoxazolinyl and the isoxazolidinylderivatives can be defined as wherein R and R are the same or differentand are each hydrogen, loweralkyl having 1-6 carbon atoms, carboxyalkyl,carboxamido, carboxamidoalkyl, carboxamidodialkyl, phenyl, or R and Rare a ring structure having the following structure:

+CH n equals an integer from 3-40;

m equals an integer from l-3; n equals an integer from l-2;

(-(CH m equals an integer from l-3;

Z equals hydrogen or benzoyl;

n equals an integer from l-4;

wherein R is hydrogen, loweralkyl having l-6 carbon atoms, or CH CH OH,to prepare the isoxazolyl derivative. The hydroxamoyl chloride isprepared from the 2-formyl-l-substituted-5-nitroimidazole followingprocedures known in the art. For example, reaction with hydroxylamine isfollowed by chlorination with nitrosyl chloride. Preparation of the2-formyl starting material is described in Belgium Pat. No. 661,262issued Sept. 17, 1965.

The acetylene and the hydroxamoyl chloride are reacted in an inertsolvent such as tetrahydrofuran, benzene, or chloroform. The molar ratioof the hydroxamoyl chloride to the acetylene is approximately 1:1,although l:ll 5 can be used. The reaction takes place in the presence ofan organic base, such as an alkylamine, for example, triethylamine,N-methyl piperidine, or any suitable tertiary amine. The temperature ofthe reaction is preferably 025C. Lower temperatures may be used, to20C., and the operable upper temperature limit is such thatsubstantially no acetylene polymerization occurs. The reaction takesplace in from one half to 10 hours.

It is noted that neither the reactive olefin nor the reactive acetylenecontain the substituents amino, aminoalkyl, or aminodialkyl, althoughthis moiety can be present on the final nitroimidazole. The process ofpreparing these functions utilizes first an olefin or an acetylenecontaining either a carboxyalkyl or a carboxamido group at any one ofpositions R R R or R The reaction with the desired nitroimidazole iscompleted as described above; the final isoxazolyl-, A isoxazolinyl-, orisoxazolidinyl-nitroimidazole is prepared. This nitroimidazole is thenhydrolyzed in acidic or basic aqueous solution to remove either thecarboxyalkyl group or the carboxamido group, thereby producing the freecarboxylic acid functionality at positions R R R or R of thecorresponding ring. Following hydrolysis, the acid chloride is preparedby reacting with thionyl chloride or oxalyl chloride. The acid chlorideis then reacted with an alkali metal azide, such as sodium, potassium,or lithium azide to prepare the acid azide of the nitroimidazole. Thislatter acid azide can be rearranged to the corresponding isocyanate byheat-' ingto reflux in an inert organic solvent such as benzene, xylene,or the like. The isocyanate can be treated with mineral acid such asHCI, H 80 or the like to prepare the free amino substituent.Alternately, the isocyanate can be reacted at elevated temperatures withmethanol in an inert organic solvent as above tov prepare the carbamate,and the latter removed by acid or base hydrolysis toyield the finalamine.

After the amine is obtained on the ring, the nitroimidazole can betreated with a loweralkyl halide, loweralkyl having l-6 carbon atoms,for instance, methyl iodide, ethyl chloride, n-butyl iodide, hexylbromide,.or the like. An inert organic solvent such as ethanol,methanol, dimethyl formamide, and an elevated temperature between 60l20C. can be used. The amino group at R R R or R is then alkylated withinl-2 hours. If a molecular equivalent is used, the secondary amine isproduced, or an aminoalkyl group at R R R or R If an excess of reagentis used, the tertiary amine, the aminodialkyl group, is produced at R RR or R If an unsymmetrical tertiary amine is desired, the reaction canbe conducted in two stages, with a molecular equivalent of each desiredalkyl halide being used in each step.

The above described acetylene can only be used to prepare an isoxazolylderivative in which R and R are not joined in a ring structure. When anisoxazolyl derivative is desired which has a cyclic substituent onpositions 4 and 5 of the isoxazole ring, a morpholinosubstituted olefinhaving the following formula:

used, for instance, tetrahydrofuran is suitable. The reaction takesplace in from one half to 2 hours at -25C. The compound thus prepared isa morpholine-substituted A -isoxazoline having the following forl: mua

This latter compound can be isolated, and treated with 5 a strongmineral acid to remove the element of morpholine thereby preparing thedesired compound:

The A -isoxazolinyl derivatives are also prepared from thel-loweralkyl-5-nitroimidazol-2-hydroxamoyl chloride by reaction of thelatter with the olefin defined above. There are two different sets ofprocess conditions. In one route, the olefin and the hydroxamoylchloride are reacted in an inert solvent at reflux. The solvent ischosen so that the reflux temperature is preferably 100l50C., and can be80-200C. The ratio of hydroxamoyl chloride to olefin is approximately1:1, although 1:1-15 can be used. The reaction takes place in about 18to 24 hours.

The other route used to prepare the A -isoxazolinyl derivative utilizesthe presence of an organic base, such as alkylamine, for example,triethylamine, N-methyl piperidine or any other suitable tertiary amine.The reaction takes place in a solvent such as tetrahydrofuran at lowtemperatures, preferably from 025C. The reaction takes place in from onehalf to 10 hours.

The isoxazolidinyl derivatives are prepared by reacting an olefin asdescribed above with an a-( l-methyl-S-nitroimidazol-Z-yl)-N-alkylnitrone of the following formula:

lll

wherein R, is hydrogen, loweralkyl having 1-6 carbon atoms, or CH CH OH,and Y is H, loweralkyl or benzyl. This nitrone can be prepared from a2-formyl-lsubstituted-5-nitroimidazole by reaction with a benzyloralkyl-substituted-hydroxylamine, such as wherein Y is hydrogen, a benzylradical or an alkyl radical having 1-6 carbon atoms. The hydroxylaminecan preferably be employed in the salt form, such as the hydrochloride,acetate, carbonate and others, or in the free base form. The tworeactants are mixed together and allowed to react at room temperature to60C. for 2-12 hours in a solvent such as methanol, ethanol, or water.The desired product can be isolated after the solution is made alkalinewith an inorganic base.

The chosen nitrone is then reacted with an olefin chosen from the groupdescribed above. The reactants are reacted in an inert solvent atreflux, and operably at a temperature of about 200C., and preferablyl0Ol50C. The ratio of nitrone to olefin is approximately 1:], althoughl:l15 can be used. The reaction takes place in about l-l2 hours.

The novel compounds of this invention have antibacterial andantiprotozoal activity especially against human and animaltrypanosomiasis, including Chagas disease, and trichomoniasis.

Trypanosomiasis is a term used to describe a group of allied protozoa]diseases, each of which is due to infection with a species of the genusTrypanosoma. They reach their greatest importance in Africa where theirpresence in enzootic form precludes the keeping of domestic animalsthroughout the largest part of the continent between l5N and 20Slatitude. The pathogenic trypanosomes of Africa are considered to beprimarily associated with the tsetse flies (glossina) which feed onvertebrate blood. Wherever tsetse are present, trypanosomiasis will alsobe found in some part of the mammalian population. The clinical findingsare typically those of a wasting disease with intermittent fever.Anemia, edema, and cachexia are parts of the syndrome.

The important trypanosomes pathogenic to domestic animals are T.congolense, T. simiae, T. vivax, and T. brucei. The latter trypanosomeis morphologically identical to T. gambiense, responsible for humansleeping sickness" of Africa. A trypanosome found in the WesternHemisphere is T. cruzi, which affects both domestic animals and man.

Acute Chagas' disease (T. cruzi) occurs predominantly in young children.The chronic form may be mild and asymptomatic, but complications frommyocarditis and CNS. involvement may result with fatal outcome.

Trichomoniasis is a protozoan disease affecting cattle, poultry, andhumans. In cattle the causative protozoan is Trichomonas foetus whichproduces a contagious venereal disease characterized by sterility,pyometra and abortion. Trichomonas gallinarum invades the lowerintestine of domestic birds and causes diarrhea and lesions in theintestinal wall. In humans the infective protozoa are Trichomonasvaginalis, infecting the vagina and prostate, and Trichomonas hominis,found in the intestine.

The compounds of this invention have particular value in the control oftrypanosomiasis and trichomoniasis in domesticated animals, particularlycattle. For this purpose, they may be administered orally with aningestible carrier as a component of the animal feedstuff, in thedrinking water, in salt blocks and in unit dosage forms such as bolusesand drenches. The amount of active ingredient required for optimumcontrol of trypanosomiasis varies in accordance with such factors as theparticular compound employed. The species of animal to be treated, thespecies of infecting parasite, the severity of infection, and whetherthe compound is employed therapeutically or prophylactically. Ingeneral, the compounds defined by Formula I, when administered orally todomestic animals in daily doses of from about 0.l mg. to about 500 mg.per kilogram of animal body weight are highly effective in controllingtrypanosomiasis and trichomoniasis without intolerable toxic effect.When these compounds are to be employed as therapeutic agents, goodresults are obtained when the animals are fed a daily dose of from aboutmg. to about 500 mg. and preferably mg. to 250 mg. per kilogram of bodyweight.

Administration may be in a single dose or divided into a plurality ofsmaller doses over a period of 24 hours. Where prophylactic treatment isdesired and the compounds are fed continuously, satisfactory results areobtained when the animals ingest daily dosages of about 0.1 mg. to 100mg. per kilogram of body weight. The unit dosage forms may be readilyprepared by conventional formulating techniques and are particularlyuseful when administration is to be made in a single dose or divideddoses over a period of 24 hours.

The exact amount of active ingredient to be employed in the abovecompositions may vary provided that a sufficient amount is ingested togive the required dosage. In general, tablets, boluses and drenchescontaining from about 5 to 70% by weight of active ingredient may besatisfactorily employed to supply the desired dosage.

The substituted imidazoles defined by Formula I above may beadministered, dispersed in or admixed with the normal elements of animalsustenance, i.e., the feed, drinking water or other liquids normallypartaken by the animals. This method is preferred when it is desired toadminister the active compounds continuously, either as a therapeutic orprophylactic agent, for a period of several days or more. However, insuch usage, it is to be understood that the present invention alsocontemplates the employment of compositions containing the activecompounds intimately dispersed in or admixed with any other carrier ordiluent which is inert with respect to the active ingredient, orallyadministrable and is tolerated by the animals.

When the compounds described according to Formula I above are providedas a constituent of the feed, the required dosage may be supplied withfeed compositions containing from about 0 .001 to 3% by weight of theactive compound; Such medicated feed compositions can be prepared fordirect use by mixing the above amount of active ingredient directly withthe feed. The medicated feedsmay also be prepared by the use of feedsupplements containing a higher concentration of the active ingredientuniformly dispersed in a solid edible carrier such as corn meal, wheatshorts, alfalfa, etc. In general, feed supplements containing from about5 to about 50% by weight of active ingredient may be satisfactorilyemployed to supply the desired dosage in the finished feed.

In the preparation of feed supplements, the active ingredient is addedto the carrier'and the whole mixed to give substantially uniformdispersion of the antitrypanosomiasis agent in the carrier.

When the substituted nitroimidazoles of'this invention are used in theprevention and treatment of Chagas disease and human sleeping sickness,the compounds can be administered as intravenous, intramuscular, orinterperitoneal injections. The compounds are suspended or dissolved inan inert non-toxic pharmaceutically acceptable carrier and administered.When used as a prophylactic, 21 2 mg./kg. of body weight are injectedevery I-8 months. The compounds can also be used orally against Chagasdisease or'human sleeping sickness. The oral dosage is-3-20 mg. per kg.twice a day for 5-10 days. This therapy can be given alone or inaddition to other drugs useful against trypanosomiasis, such as sodiumsuramin, melarsoprol, tryparsamide, or pentamidine.

The compounds of the present invention are also useful as topical trichomonacides. When employing the compounds in this manner, one or more ofthe active agents are uniformly distributed in asuitablechemotherapeutic vehicle that is chemically compatiblewith theparticular compound selected, non-inhibiting with respect to the actionof the effective agent upon the parasite and essentially non-injuriousto body tissue under the conditions of use. The vehicle is preferably asemi-liquid or semi-solid type andthe final preparation may be in'theform of a suppository if desired.

Oil and water types of emulsions or creams as well as aqueous jelliessuch as thosqiprepared with the aid of any of a number of commerciallyused jelling agents including acacia, tragacanth, bentonite, alginicacid and the like are suitable vehicles. The vehicle may also be aviscous aqueousgel containingone or more cellulose derivatives such asmethyl cellulose, hydroxyethyl cellulose, and sodium carboxymethylcellulose. Gelling agents such as pectin, gum tragacanth, sodiumalginate and other vegetable gelling agents are also useful vehiclesinthis regard.

This invention is more fully described in a reading of the followingexamples. The first four examples show the preparation of theS-nitroimidazole starting materials. These preparations are exemplaryonlyto show one of several possible methods of preparing thesecompounds.

EXAMPLE 1 l- Methyl-S -nitroirnidazole I 24.2 6., (0.214 moles) of4(5)-nitroimidazole is heated with 24.0 g. (0." mole) of methyl tosylatefor 1 hour at ll90C. and cooled to gi.Ve.,a hard solid. The mixture isshaken with l.75.ml.' -of2.5 iNaqueous sodium hydroxide until it isdissolved and diluted with 175 ml. of water to give an oily precipitate.The mixture is extracted with ether; the ether extract washed with 2.5 Naqueous hydrochloric acid and water. The aqueous acid wash is treatedwith excess aqueous sodium hydroxide and extracted with ether. Thislatter ether extract is evaporated to dryness and recrystallized frompetroleum ether to yield l-methyl-5- nitroimidazole, m.p. l54l55C.

In accordance with the above procedure but starting with ethyl tosylate,propyl tosylate, or n-butyl tosylate in place of methyl tosylate, thereis obtained l-ethyl-S- nitroimidazole, 1-propyl-5-nitroimidazole, andl-nbutyl-S-nitroimidazole.

EXAMPLE 2 l-Methyl-2-hydroxymethyl-5 -nitroimidazole 27.9 g. ofl-methyl-5-nitroimidazole prepared as in Example 1 and 30.1 g. ofparaformaldehyde are added to 154 ml. of dimethylsulfoxide and theresulting solution is sealed into a glass-lined tube. The solution isheated at 110C. for 24 hours, with shaking. The dimethylsulfoxide isremoved by distillation at 53-56C./2 mm. The residue is extracted with 3X 150 ml. of hot benzene. The benzene extracts are combined and cooledto room temperature. l-Methyl-2-hydroxymethyl-S-nitroimidazolecrystallizes, and is recovered by filtration. The yield of product is 23g., m.p. ll2-l14.5C.

When l-ethyl-5-nitroimidazole, l-propyl-5- nitroimidazole,l-n-butyl-5-nitroimidazole, and 4(5)- nitroimidazole are used in theabove reaction, respectively, the following compounds are prepared:l-ethyl- 2-hydroxymethyl-5-nitroimidazole;l-prpyl-2-hydroxymethyl-Snitroimidazole; l-n-butyl-2-hydroxymethyl-S-nitroimidazole; and 2-hydroxymethyl-5- nitroimidazole.

EXAMPLE 3 l-Methyl-2-formyl-5-nitroimidazole 100 g. (0.64 mole) ofl-methyl-2-hydroxymethyl-5- nitroimidazole prepared as in Example 2 isdissolved in 3500.ml. of benzene at 70C. There is added over a 20 minuteperiod 460 g. of lead tetraacetate (previously washed with glacialacetic acid and air dried in the dark). The reaction mixture is stirredat 78C. for 8 hours during which time white, crystalline lead diacetateprecipitates from the solution. The mixture is allowed to standovernight at room temperature, and the lead diacetate then removed byfiltration and washed with 2 X 100 ml. of benzene. The combined benzenefiltrate and washes are extracted with 1500 ml. of water and then withtwo 1 liter portions of saturated aqueous potassium bicarbonate.

The dried extracts are evaporated in vacuo to give a residue ofsubstantially pure l-methyl-2-formyl-5- nitroimidazole.Recrystallization of the product from 500 ml. of boiling hexane affords79 g. of l-methyl-2- formyl-S-nitroimidazole, m.p. 9094C.

When this general procedure is followed using 1-ethyl-2-hydroxymethyl-5-nitroimidazole, l-propyl-2-hydroxymethyl-S-nitroimidazole,l-n-butyl-2-hydroxymethyl-S-nitroimidazole, and 2-hydroxymethyl-5-nitroimidazole, the following compounds are respectively prepared:l-ethyl-2-formyl-5-nitroimidazole; 1- propyl-2-formyl-5-nitroimidazole;l-n-butyl-Z-formyl- -nitroimidazole; and 2-formyl-5-nitroimidazole.

EXAMPLE 4 l-( 2 '-Acetoxyethyl )-5 -nitroimidazole 4.0 g. of4(5)-nitroimidazole and 4.7 ml. of B-ethoxyethyl tosylate are heatedtogether in a ll75C. oil bath for 1 hour with occasional stirring untilthe mixture become homogeneous. The mixture is cooled to near roomtemperature and dissolved by agitating with a mixture of about 50 ml. ofchloroform and 50 ml. 4N

ammonium hydroxide. The chloroform phase is extracted twice with 2Nammonium hydroxide and dried over sodium sulfate. Evaporation to drynessin vacuo gives a black syrup which is filtered through 30 g. of basicalumina eluting with l,2-dichloroethanezether. The very pale yellow bandwhich comes through the column fairly rapidly is collected andevaporated in vacuo to give a yellow oil which crystallizes on seeding.The crude product is recrystallized from ether-hexane giving pale browncrystals of l-(2-ethoxyethyl)-5- nitroimidazole.

57 mg. of the above product is heated at C. in .3 ml. concentratedsulfuric acid for one-half hour. The

mixture is diluted with 1.5 ml. water and heated an additional hour. Thesolution is treated with charcoal, diluted with 1 ml. water and treateddropwise with 0.7 ml. of 11.7 N sodium hydroxide while cooled in ice.The crystalline precipitate which forms is filtered off, washed withwater and air dried. This material is recrystallized from benzene andthen with charcoal treatment from methanol-water givingl-(2'-hydroxyethyl)- S-nitroimidazole, m.p. l0llO2C.

Acetylation of 15 g. of the latter product with 10 g. of aceticanhydride in 30 ml. of pyridine at reflux for 20 minutes yieldsl-(2-acetoxyethyl)-5- nitroimidazole, m.p. 6l62C.

EXAMPLE 5 l-(2 -Acetoxyethyl)- 2-formyl-5-nitroimidazole A mixture of24.25 g. of l-(2-acetoxyethyl)-5- nitroimidazole prepared as in Example4, 15 g. of paraformaldehyde and ml. of dimethylsulfoxide is heated in asealed tube overnight at l00l50C. The dimethylsulfoxide is removedcompletely at reduced pressure, and the residue is dissolved in waterand extracted with chloroform. The chloroform extract is dried andconcentrated. The residue is dissolved in ethyl acetate, and thesolution is charged on a column of alumina. Elution with ethyl acetateand evaporation of the solvent yields1-(2-acetoxyethyl)-2-hydroxymethyl-S-nitroimidazole, m.p. l38145C.

This compound is then treated following the procedure of Example 1 withlead tetraacetate. After purification,1-(2'-acetoxyethyl)-2-formyl-5-nitroimidazole is identified.

This latter compound can be used in any of the following Examples whichuse the starting 2-formyl- 1 substituted-S-nitroimidazoles of Example 3.After using this compound to form the desired cyclic-substitutednitroimidazole, the acetate can be removed using hydrolysis to yield thedesired 1-(2'-hydroxyethyl)-2-substituted-S-nitroimidazole.

The following Example, Example 6, shows the preparation of the nitroneof Formula III. Example 7 is the preparation of the hydroxyamoylchloride of Formula 11.

EXAM PLE 6 a-( l-Methyl-5-nitroimidazol2-yl)-N-methylnitrone To asolution of 1-methyl-2-formyl-5-nitroimidazole prepared as in Example 3,(4.65 g., 0.03 mole) in 75 ml. of methanol is added 2.5 g. (0.03 mole)of N-methylhydroxylamine hydrochloride CH NHOH.HCl. The mixture isallowed to stand at room temperature for 4 hours. A precipitate formswhich is recovered and dissolved in 40 ml. of water.

Solid sodium bicarbonate is added until the solution has a basic pH anda precipitate deposits again. After filtration and recrystallizationfrom methanol, 1.8 g. of the product,a-(l-methyl-5-nitroimidazol-2-yl)-N- methylnitrone is recovered having amelting point of 180C. (with decomposition).

The corresponding a-(1-ethyl-5-nitroimidazol-2-y1)- N-methylnitrone,a-(1-propyl-5-nitroimidazol-2-yl)-N- methylnitrone, anda-[1-(2'-acetoxyethyl)-5- nitroimidazol-Z-yl]-N-methylnitrone can beprepared in a similar fashion utilizing the respectively 1-substituted-2-formyl-5-nitroimidazoles disclosed in Examples 3 and 5.The corresponding a-(l-methyl-S- nitroimidazol-2-yl)-N-benzylnitrone canalso be prepared using N-benzylhydroxylamine hydrochloride in the abovereaction with 1-methyl-2-formyl-5- nitroimidazole.

EXAMPLE 7 1-Methyl-5-nitroimidazole-2-hydroxamoylchloride 15.5 g. of1-methyl-2-formyl-5-nitroimidazole prepared as in Example 3 is dissolvedin 300 ml. of ethanol and heated to 80C. The mixture is added to a hotsolution of 7.65 g. of NH OHJ-ICI in 30 ml. of water. The mixture isrefrigerated overnight. Filtration and crystallization yielded a yellowcrystalline material, having a melting point of 251252C. (dec.). Thisintermediate oxime product is dissolved in 50 ml. of dimethylformamideat C. A solution of NOCl (13.1 g. in 200 ml. of dimethylformamide) isadded dropwise with stirring.

The mixture is stirred at 0C. for 15 minutes and 45 minutes at roomtemperature. It is quenched by pouring into 2500 ml. of cold water, andthe precipitate filtered, washed and dried. A sample is recrystallizedfrom ethyl acetate and dried under vacuum. The product obtained has amelting point of 185186C. and is identified as1-methyl-5-nitroimidazole-2- hydroxamoylchloride. The corresponding1-(2'- acetoxyethyl)--nitroimidazole-2- hydroxamoylchloride,l-ethyl-5-nitroimidazole-2- hydroxamoylchloride,1-n-butyl-5-nitroimidazole-2- hydroxamoylchloride, and5-nitroimidazole-2- hydroxamoylchloride are prepared respectively from1-( 2 -acetoxyethyl )-2-formyl-5-nitroimidazole, 1-ethyl-2-formyl-5-nitroimidazole, 1-n-butyl-2-formyl-5- nitroimidazole,and 2-formyl-5-nitroimidazole prepared as in Examples 3 and 5.

The following Examples 8 to 35 all have the structural formula given.However, only the oxygencontaining ring is drawn. When the N1 is used,it is meant to be the corresponding nitroimidazol-2-yl ring.

EXAMPLE 8 l-Methyl-2-(2-methyl-5-carboxymethyl-isoxazolidin-3-yl)-5-nitroimidazole N oocH.

The compound prepared in Example 6, a-( l-methyl-5-nitroimidazol-2-yl)-N-methylnitrone (4.0 g.) is added to 50 ml. ofmethylacrylate and is refluxed at about C. for 1 hour. At the end ofthis time, excess methylacrylate is removed under vacuum. The residue ispurified by recrystallization from methanol. The product recovered isidentified as l-methyl-2-(2-methyl-5-carboxymethyl-isoxazolidin-3-yl)-5- nitroimidazole having amelting point of l05l06C. The corresponding benzyl derivative,l-methyl-2-(2- benzyl-5-carboxymethyl-isoxazolidin-3-yl) 5-nitroimidazole is prepared using a-(l-methyl-S-nitroimidazol-Z-yl)-N-benzylnitrone.

EXAMPLE 9 l-Methyl-2-(2-methyl-4,5-hexamethyleneisoxazolidin-3-yl)-5-nitroimidazolehydrochloride 1.87 g. of the compound prepared in Example 6, a-(l-methyl-5-nitroimidazol-2-yl)-N-methylnitrone, and 1.1 g. ofcyclooctene are added in 30 ml. of toluene. The mixture is refluxed forabout 16 hours. At the end of this period, the nitrone is dissolved. Thereaction mixture, after filtering, is evaporated to a yellow oil. Thisoil is purified by chromatographic techniques on silica gel with abenzene:chloroform eluent. 2.5 g. of a clear yellow oil is obtained.This oil is then mixed with ether containing dry hydrochloric acid toobtain 2.4 g. of a crystalline material. After recrystallization from2-propanol, a solid is obtained having a melting point of 193C. withdecomposition. This solid is identified as 1-methyl-2-(2-methyl-4,5-hexamethylene-isoxazolidin- 3-yl)-5-nitroimidazolehydrochloride. The analogous compound prepared using a-( l-methyl-S-nitroimidazol-2-yl)-N-benzylnitrone is identified aslmethyl-2-(2-benzyl-4,5-hexamethylene-isoxazolidin-3-yl)-5-nitroimidazole hydrochloride.

EXAMPLE l0 ONH 5.52 g. of the nitrone prepared in Example 6 is refluxedwith 2.34 g. of acrylamide in 100 ml. of tetrahydrofuran. After 3 hours,an additional 1.0 g. of acrylamide in 40 ml. of tetrahydrofuran is addedand refluxing continued. After 12 hours, the reaction mixture is cooledand filtered. After purification, 3.4 g. of the product,1-methyl-(2-methyl-5-carboxamidoisoxazolidin-3-yl)-5-nitroimidazole,having a melting point of 2l4-2l5C. (dec.) is recovered. Thecorrespondingl-methyl-2-(2-benzyl-5-carboxamidoisoxazolidin-3-yl)-5-nitroimidazole isprepared using the N-benzylnitrone described in Example 6.

The product1-methyl-2-(Z-methyI-S-carboxamidoisoxazolidin-3-yl)-5-nitroimidazole isthen heated in an acidic solution to recover the hydrolysis product, 1-methyl-2-(2-methyl-5-carboxylic acid-isoxazolidin-3-yl)-5-nitroimidazole. This latter product, after treating following theprocedure of Example 13, yields 1-methyl-2-(2-methyl-5-amino-isoxazolidin-3-yl) -nitroimidazole.

EXAMPLE l1 l-Methyl-2-[ Z-methyI-S-(N-methyl)-carboxamidoisoxazolidin-3-yl]-5-nitroimidazole CONHCH 5.4 g. of thenitrone prepared in Example 6 is refluxed with 2.5 g. ofN-methylacrylamide in 100 ml. of tetrahydrofuran. After 2 hours, anadditional 1.0 g. of N-methylacrylamide in 40 ml. of tetrahydrofuran isadded and refluxing continued. After 8 hours, the reaction mixture iscooled and filtered. After purification, the product,l-methyl-2-[2-methyl-5-(N-methyl)-carboxamido-isoxazolidin-B-yl]-5-nitroimidazole, is recovered.

In an analogous manner, using N-benzylnitrone and N-ethylacrylamide; orN-benzylnitrone and N- hexylacrylamide, the corresponding products, 1-methyl-2-[Z-benzyl-S-(N-ethyl)-carboxamidoisoxazolidin-3-yll-5-nitroimidazoleand 1-methyl-2-[2- benzyl-5-(N-hexyl)-carboxamido-isoxazolidin-3-yl]-5-nitroimidazole are prepared.

Also, when N,N-dimethylacrylamide or N-methyl-N- propylacrylamide areemployed in the above reaction with the nitrone as prepared in Example6, the productsl-methyl-2-[2-methyl-5-(N,N-dimethyl)-carboxamidoisoxazolidin-3-yl]-5-nitroimidazoleand l-methyl-2-[2-methyl-5-(N-methyl-N-propyl)-carboxamidoisoxazolidin-S-yl]-5-nitroimidazoleare formed.

EXAMPLE l2 l-Methyl-2-( 5-carboxyethylisoxazol-3-yl )-5- nitroimidazole8.2 g. of the hydroxamoylchloride prepared in Example 7 are dissolved in160 ml. of tetrahydrofuran at 0C. To the solution is added a coldsolution of triethylamine tetrahydrofuran (0.04 mole in 40 ml.). Afterone minute, a solution of ethylpropiolate (5.0 g.) in 10 ml. oftetrahydrofuran is added. The reaction mixture is stirred at 0C. forone-half hour and then at room temperature for 1 hour. The mixture isthen filtered and the filtrate is reduced under vacuum leaving an orangecrystalline mass. After recrystallization from ethanol, the product isobtained which has a melting point of 114-l 15C. This product isidentified as l-methyl-Z-(5-carboxyethylisoxazol-3-yl)-5-nitroimidazole.

EXAMPLE l3 l-Methyl'2-( S-carboxamido-isoxazol-3-yl )-5 nitroimidazoleCONH,

3 g. of the compound prepared in Example 12 is dissolved in hotmethanol. The solution is saturated with ammonia. A precipitate isformed and the mixture is cooled by placing in the refrigerator. Afterfiltration and purification, the pure product having a melting point of23523 8C. is recovered. This product is identified asl-methyl-2-(5-carboxamido-isoxazol-3-yl)-5- nitroimidazole.

EXAMPLE l4 1-Methyl-2-(5-aminoisoxazol-3-yl)-5-nitroimidazole1-Methyl-2-(5-aminomethylisoxazol-3-yl)-5- nitroimidazolel-Methyl-2-(5-aminomethylhexylisoxazol-3-yl)-5- nitroimidazole 4 g. ofthe compound prepared in Example 13, 1-methyl-2-(5-carboxamidoisoxazol-Z-yl)-5- nitroimidazole, are dissolvedin 30 ml. ofa 10% HCl solution, and the mixture heated to reflux. After30 minutes, the reaction is terminated and the product, l-methyl-2-(S-carboxylic acid-isoxazol-3-yl)-5- nitroimidazole, is obtained.

1.5 g. of the acid prepared above are refluxed in oxalyl chloride (25ml.) until a clear solution is obtained, after about 6 hours. Excessreagent is removed under vacuum. The product, l-methyl-2-(5-carboxylicacid chloride-isoxazol-3-yl)-5-nitroimidazole is dissolved in 50 ml.acetone. A solution of sodium azide (0.4 g. of NaN in 5 ml. of water isadded all at once. After stirring for 15 minutes, an additional ml. ofwater is added and stirring continued for another 15 minutes.

The product is l-methyl-2-(5-carboxylic acidazideisoxazol-3-yl)-5-nitroimidazole. 1.4 g. of the latter is dissolvedin 60 ml. of benzene and refluxed for 3 hours. ml. of concentrated HClare then added and refluxing continued for one-half hour. The reactionis diluted with chloroform and made basic. The dried organic phaseyielded 0.5 g. of the product, 1-methyl-2-(5-aminoisoxazol-3-yl)-5-nitroimidazole, m.p.

0.25 g. of l-methyl-2(5-aminoisoxazol-3-yl)-5- nitroimidazole, preparedabove, are dissolved in 20 ml. of dimethylformamide, 0.16 g. of methyliodide are added, and the reaction mixture is heated to 80 for 1 hour.The solvent and unreacted reagents are removed, and the productrecrystallized. The product is 1-methyl-2-(5-aminomethyl-isoxazol-3-yl)-5- nitroimidazole.

The product prepared above is treated in a similar fashion with hexylchloride in dimethylformamide for two hours. The recrystallized productis identified as 1-methyl-2-(S-aminoethylhexylisoxazol-3-yl)-5-nitroimidazole.

EXAMPLE 1-Methyl-2-(4,5 ,6,7-tetrahydrocyclohex[d ]isoxazol-3-yl)-5-nitroimidazole To a suspension of 2.04 g. of the hydroxamoylchloride prepared in Example 7 in 30 ml. of tetrahydrofuran at 0C. isadded a solution of triethylamine andl-morpholino-3,.4,5,6-tetrahydrobenzene (1.01 g. of triethylamine and1.67 g. of the morpholino compound). The mixture is stirred 15 minutesat 0C. and one-half hour at room temperature. The tetrahydrofuran isevaporated. The residue is dissolved in dichloromethane and is washedwith sodium bicarbonate solution. The organic phase is dried andevaporated to a yellow oil. After treatment with diethyl ether, acrystalline product is obtained. A sample recrystallized from methanolhas a melting point of l53l56C. This product is an intermediate in thesynthesis and-is a A isoxazoline compound with a morpholino substituent.It is identified as l-methyl-2-(4,5-tetramethylene-5- morpholino-A-isoxazolindin-3-yl)-5-nitroimidazole,

mp. 155C.

This latter morpholino compound 10 g.) is dissolved in concentratedsulfuric acid (100 ml.) and heated on a steam bath for 1% hours. Theyellow reaction mixture is poured onto ice to quench. After filtration,a crude product is obtained. It is recrystallized frommethanol andyields 4.5 g. of a product identified as l-methyl-2-(4,5,6,7-tetrahydro,cyclohex[d]isoxazol-3-yl)-5- nitroimidazole, havinga melting point of 161l62C.

The following Examples 16 through 36 relate .to the prepartion of the A-isoxazoline. It will be clear to. one skilled in the art that, althoughthe l-methyl derivatives are prepared, the other loweralkyl,acetoxyethyl, and unsubstituted derivatives can be prepared from thecorl6 responding hydroxamoyl chloride compounds in Example 7.

To a solution of the hydroxamoyl chloride compounds prepared in Example7 in tetrahydrofuran (4.02 g. in 80 ml.) at 0C. is added with stirring2.7 ml. of methylacrylate. Following this addi tion, asolution oftriethylamine in tetrahydrofuran (2.02 g. in ml.) is added dropwise tothe solution. The mixture is stirred 10 minutes at 0C. then 1 hour atroom temperature. The triethylamine hydrochloride is filtered and thentetrahydrofuran is removed under vacuum. The residue is taken up inchloroform and washed with a dilute solution of sodium bicarbonate.After drying, the organic layer is evaporated and the residual yellowoil is crystallized. The product is identified as l-methyl-2-(5-carboxymethyl-A -isoxazolin-3-yl)-5-nitroimidaz0le,

and has a melting point of,l09l 10C.

EXAMPLE17 l-Methyl-2-(5-carboxamido-A -isoxazolin3-yl)-5-nitroimidazolei I The compound prepared in Example: 16 i sidiissolved inmethanol 119 mg. in 10 ml.). Ammoniais bubbled through the solutionuntil aprecipitateformed. The mixture is filtered after 1 hour andpurification and recrystallization yield 95 mg. ofthe product,l-methyl-2- (5-carboxamido-A -isoxazolin 3-yl)-5-nitroimidazole,

having a meltingpoint'of 23 8239C; This latter compound can be treatedfollowing the-procedurei-offExamnitroimidazole 2.04 g. of thehydroxyamoylchloride prepared in Example 7 are dissolved in 40 ml. oftetrahydrofuran. One gram of styrene is added and the solution is keptat C. while a solution of triethylamine tetrahydrofuran (1.01 g. in 10ml.) is added. The mixture is stirred 15 minutes at 0C. and 1 hour atroom temperature. After filtering and removing the excess solvent, theresidue is taken up in chloroform and washed with a dilute solution ofsodium bicarbonate. Evaporation of the dried extract yields a yellow oilwhich recrystallizes from methanol as a pale yellow crystallinematerial. This material has a melting point of l33134C. and isidentified as lmethyl-2-(5-phenyl-A -isoxazolin-3-yl)-5- nitroimidazole.

EXAMPLE l9 1-Methyl2-(4,5-cyclodimethylsulfone-A -isoxazolin-3- yl)--nitroimidazole 0.408 g. of the hydroxyamoylchloride prepared inExample 10 are dissolved in 8 ml. of tetrahydrofuran at 0C. To thissolution is added dropwise with stirring a 0.202 g/sblution oftriethylamine in 2 ml. of tetrahydrofuran. The mixture is stirred forminutes at 0C. and 1 hour at room temperature. After filtering andremoving the solvent, the residue is treated with chloroform and washedwith sodium bicarbonate solution. The dried organic layer afterpurification and recrystallization yields a product identified as1-methyl-2-(4,5- cyclodimethylsulfone-A -isoxazolin-3-yl)-5-nitroimidazole, having a melting point of 208-209C.

EXAMPLE 2O l-Methyl-2-( 3a,5,6,7a-tetrahydro-4H-pyrano[ 3,2-disoxazol-3-yl)-5-nitroimidazole Following the same general procedure ofExamples 16 through 19, the hydroxyamoylchloride prepared as in Example7 is reacted with dihydropyran at 0C. The product, afterrecrystallization, is identified aslmethyl-2-(3a,5,6,7a-tetrahydro-4H-pyrano[3,2-d]-isoxazol-3-yl)-5-nitroimidaz0le, having a melting point of l40l42C.

EXAMPLE 21 l-Methyl-2-( 3a,4,6,6a-tetrahydro-4,6-dioxo-4H- pyrrolo[3,4-d]-A -isoxazol-3-yl)-5-nitroimidazole EXAMPLE 22 1-Methyl-2-( 5hexyl-A -isoxazolin-3 -y] )-5 nitroimidazole Following the same generalprocedure of Examples 16 through 19, the hydroxyamoylchloride preparedas in Example 7 is reacted with octene-l. The product, afterrecrystallization, is identified as l-methyl-2-(5- hexyl-A-isoxazolin-3-yl)-5-nitroimidazole, having a melting point of 50-51C.

EXAM PLE 23 1-Methyl-2-(A -isoxazolin-3-yl)-5 -nitroimidazole Followingthe same general procedure of Examples 16 through 19, thehydroxamoylchloride prepared as in Example 7 is reacted with ethylene.The product, after recrystallization, is identified as 1-methyl-2-( Aisoxazolin-B-yl)-5-nitroimidazole, having a melting point of l03-l05C.

EXAMPLE 24 l-Methyl-2-(4,5-cis-dimethyl-A isoxazohn-3-yl)-5-nitroimidazole Following the same general procedure of Examples 16through 19, the hydroxamoylchloride prepared as in Example 7 is reactedwith cis-2-butene. The product,

after recrystallization, is identified as 1-methyl-(4,5- cis-dimethyl-A-isoxazolin-ll-yl)--nitroimidazole, having a melting point of 8384C.

EXAMPLE 25 l-Methyl-2-( 4,5-trans-dimethyl-A -isoxazolin-3-yl )-5-nitroimidazole Following the same general procedure of Examples 16through 19, the hydroxyamoylchloride prepared as in Example 7 is reactedwith trans-2-butene. The product, after recrystallization, is identifiedas l-methyl-Z- (4,5-trans-dimethyl-A -isoxazolin-3-yl)-5-nitroimidazole, having a melting point of 65-67C.

EXAMPLE 26 Exo-2-(3a,4,5 ,6,7,7a-hexahydro4,7-methano-l ,2-benzisoxazol-3-yl l -methyl-5-nitroimidazole Following the same generalprocedure of Examples 16 through 19, the hydroxamoylchloride prepared asin 4 Example 7 is reacted with norbornene. The product,

exo-Z- after recrystallization, is identified as (3a,4,5,6,7,7a-hexahydro-4,7-methano-l,2-benzisoxazol-3-yl)-l-methyl-5-nitroimidazole, having a melting pointof l24l25C.

EXAMPLE 27 l-Methyl-2-( 5-benzoyl-3a,5 ,6,6a-tetrahydro-4H- pyrrolo[ 3,4-d l-isoxazol-3-yl )-5-nitroimidazole Following the same generalprocedure of Examples 16 through 19, the hydroxamolychloride prepared asin Example 7 is reacted with N-benzoyl-2,5-dihydropyrrole. The product,after recrystallization, is identitied as4H-pyrrolo[3,4-d]-isoxazol-3-yl)-5-nitroimidazole, having a meltingpoint of l53155C.

l-methyl-2-( 5-benzoyl-3a,5 ,6,6a-tetrahydro- 5 EXAM PLE 28 transl-Methyl-2-[ 3a,4 ,5 ,6,7,8,9,9aoctahydrocyclooct[d ]-isoxazol-3- yl]-5-nitroimidazole Following the same general procedure of Examples 16through 19, the hydroxamoylchloride prepared as in Example 7 is reactedwith trans-cycloocetene. The product, after recrystallization, isidentified as trans-lmethyl-2-[3a,4,5,6,7,8,9,9a-octahydrocyclooct[d]-isoxazol-3-yl]-5-nitroimidazole, having a melting point of l06-lO9C.

EXAMPLE 29 l-Methyl-2-( 3a,4,5 ,6,7,7a-hexahydro-4H-cyclohex[d1-isoxazol-3-yl )-5-nitroimidazole Following the same general procedure ofExamples 16 through 19, the hydroxyamoylchloride prepared as in Example7 is reacted with cyclohexene. The product, after recrystallization, isidentified as l-methyl-2-(3a,4,5,6,7,7a-hexahydro-4H-cyclohex[d]-isoxazol-3-yl)-5-nitroimidazole, having a melting point ol 89.59l.5C.

EXAMPLE 30 l-Methyl-2-( 3a,4,5 ,6,7,8,9,9a-octahydrocyclooct[d]-isoxazol-3-yl )-5-nitroimidazole EXAMPLE 31l-Methyl-2-(3a,4,5,6,7,7a-hexahydro-l,2-benzisoxazol-3-yl)-5-nitroimidazole N l H2 5 CH, /CH H Following thesame procedure as in Example 30, the hydroxyamoylchloride prepared as inExample 7 is reacted with cyclohexene. The product, 2-(3a,4,5,6,7,7a-

hexahydrol ,2-benz-isoxazol-3-yl )-5-nitroimidazole has a melting pointof l19-l21C.

EXAMPLE 32 lMethyl-cis-2-( 3a,5 ,6,7,8 ,8a-hexahydro-4H-cycl0hept[d]-isoxazol-3-yl)-5-nitroimidazole 20 H,-cH\

Following the same procedure as in Example 30, the hydroxamoylchlorideprepared as in Example 7 is reacted with cycloheptene. The product,l-methyl-cis-2- (3a,55,73,Sa-hexahydroAl-l-cyclohept[dl-isoxazol-3-yl)-5-nitroimidazole, having a melting point of 93-95C.

EXAMPLE 331-Methyl-trans-2-(3a,4,5,6,7,8,9,10,11,12,13,13adodecahydrocyclododec d]-isoxazol-3-yl )-5- nitroimidazole Following the same procedure as inExample 30, the

hydroxamoylchloride prepared as in Example 7 is reacted withcyclododecene. The product,l-methyltrans-2-(3a,4,5,6,7,8,9,10,.11,12,13,13adodecahydrocyclododec[d]-isoxazol-3-yl)-5- nitroimidazole, having a melting point ofl2l-l22C.

EXAMPLE 34 lMethyl-24trans-4,5-dipropyl-A -isoxazolin-3-yl )-5-nitroimidazole /"a CH,

"on, H

6.12 g. of the hydroxyamoylchloride prepared as in Example 7 is refluxedwith 3.4 g. of trans-4-octene for 18 hours. The reaction mixture is thenworked up following a similar procedure as in Example 30. The productobtained, l-methyl-2-(trans-4,5-dipropyl-Aisoxaz0lin-3-yl)-5-nitroimidazole, has a melting point of 34-36C.

EXAMPLE 35 1-Methyl-2-( trans-4,5-diethy1-A -isoxazolin-3-yl)5nitroimidazole 'CH CH Following the same procedure as in Example 34, thehydroxyamoylchloride is reacted with trans-3-hexene. The product,l-methyl-2-( trans-4,5-diethyl-A isoxazolin-3-yl)-5-nitroimidazole, hasa melting point of 6667C.

EXAMPLE 36 l-Methyl-2-( 4,5-hexano-e-lactam-A -isoxazolin-3-yl)-5-nitroimidazole CH --CH Following the same procedure as in Example 33,the hydroxyamoylchloride is reacted with 6-amino-2- hexenoic acidlactam:

The product, l-methyl-2-(4,5-hexano-e-lactam-Aisoxazolin-3-yl)-5-nitroimidazole is recovered.

We claim:

1. A 1,2-disubstituted-S-nitroimidazole having the following structure:

1. A 1,2-DISUBSTITUTED-5-NITRIMIMIDAZOLE HAVING THE FOLLOWING STRUCTURE:2. The compound of claim 1 which is 1-methyl-2-(5-carboxamido-Delta2-isoxazolin-3-yl)-5-nitroimidazole.